chemistry salt analysis cheat sheets

7/23/2019 Chemistry Salt Analysis Cheat Sheets

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Only important stuff for CBSE Class12th Chemistry practical syllabus has

been included, not everything.

Test mentioned next to group is thepreliminary test; the ones mentioned

under an anion are confirmatory testsfor it.

Group I (dilute H2SO4 group) -CO32-(carbonate), SO32- (sulphite),S2-(sulphide), NO2- (nitrite): Salt +dil H2SO4

1. No reaction: Group I anion notpresent. Continue to group II.

2. Carbonate: Colourless andodourless gas (CO2)1. WE 1 + MgSO4 = white ppt

3. Sulphite: Colourless gas withpungent smell1. WE + BaCl2 (aq) = white ppt

soluble in dil HCl

1 Water extract: Pinch of salt + water

2. WE + acidified K2Cr2O7 2 = sol3 turns green

3. WE + acidified KMnO4 = pinkcolour of KMnO4 is discharged

4. Sulphide: Colourless gas with a

smell of rotten eggs (H2S); turnslead acetate paper black1. Sodium nitroprusside test: WE

+ sodium nitroprusside 4 =purple / violet colour

2. Lead acetate test: WE + leadAcetate 5 (aq) = black ppt

5. Nitrite: Pungent light brown gas1. Starch-iodide test: WE + dil

H2SO4 (or dil acetic acid); boil,then add solid KI + freshstarch sol = deep bluecolouration

Group II (conc H2SO4 group) - Cl-(chloride), Br- (bromide), I- (iodide),

NO3- (nitrate), CH3COO-(acetate),C2O42-

(oxalate): Salt + conc H2SO4

1. No reaction: Group II anion notpresent. Continue to group III.

2. Chloride: Colourless whitepungent fumes (HCl); intensifywhen glass rod dipped in NH4OHis brought near mouth of testtube

1. Silver nitrate test: WE +AgNO3 = white ppt soluble inNH4OH

2. Chromyl chloride test: Salt +solid K2Cr2O7 + 2-3 drops concH2SO4 = orange / red fumes ofchromyl chloride 6

1. Vapours + NaOH (aq) =yellow solution

2. Yellow solution + aceticacid + lead acetate sol =

yellow ppt

2 Potassium dichromate 3 Solution4 Na2[Fe(CN)5NO]

5 Pb(CH3COO)2 6 CrO2Cl2


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= white ppt; ppt dissolves

when dil HNO3 is added and

3. Bromide: Reddish brown vapour1. Silver nitrate test: WE +

AgNO3 (aq) = yellow pptpartially soluble in NH4OH

2. Organic layer test: WE + CCl4

+ 1 drop conc HNO3 = Upperlayer aqueous; lower layerorganic of orange / browncolour (bromine is soluble innon-polar solvent)

4. Iodide: Violet vapours1. Silver nitrate test: WE +

AgNO3 (aq) = yellow pptinsoluble in NH4OH

2. Organic layer test: WE + CCl4+ 1 drop conc HNO3 = Upperlayer aqueous; lower layerorganic of violet colour (iodineis soluble in non-polar solvent)

5. Nitrate: Brown fumes withpungent smell, which intensify onadding paper pellets (may needheating)1. Brown ring test: WE + freshly

prepared FeSO4 sol + 1 dropconc HNO3 added along sideof test tube = brown ring

formed at junction of sol andacid

6. Acetate: Pungent vapour withvinegar-like smell1. Ester test: Salt + conc H2SO4

+ ethanol = fruity smell of

ester

2. Ferric chloride test: WE +FeCl3 (aq) = brick red colour1. Add dil HCl = red colour

disappears2. Add water and boil =

reddish brown ppt

7. Oxalate: Colourless gas witheffervescence (CO + CO2)1. Calcium chloride test: WE +

acetic acid + CaCl2 (aq) + boil

warmed2. Potassium permanganate

test: Salt + dil H2SO4 + heat;then add 2-3 drops KMnO4 sol= pink colour of KMnO4 is

discharged

Group III anions (special group)- SO42- (sulphate), PO43-

(phosphate): Nogroup reagent

1. Sulphate:1. Barium chloride test: WE +

BaCl2 (aq) = white pptinsoluble in conc HCl

2. Lead acetate test: WE + leadacetate (aq) + acetic acid =

white ppt soluble inCH3COONH (ammoniumacetate)

2. Phosphate:1. Ammonium molybdate test:

WE + dil HNO3 + ammoniummolybdate 7 + boil =

crystalline canary yellow ppt

Group reagent is mentioned nextto group cations.

Test mentioned next to cation isthe preliminary; ones under it

are confirmatory tests for it. When sulphate is detected, Ba2+,

Ca2+, Pb2+, and Sr2+ are notpresent as sulphates of theseradicals are insoluble.

When phosphate is detected,cations of group III and later areabsent.

7 (NH4)2MoO4


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Group 0 - NH4+ (ammonium): Nogroup reagent

1. Sodium hydroxide test: Salt +NaOH = pungent smelling gas;gives white fumes when a glassrod dipped in conc HCl is brought

near mouth of test tube2. Nessler's reagent 8 test: OS 9 +

NaOH + Nessler's reagent =Brown / yellow ppt

Group I - Pb2+ (lead):OS + dil HCl = white ppt; add water,boil, and divide into three parts

1. Leave OS undisturbed = whitecrystals formed on cooling

2. Potassium iodide test: OS + KI =yellow ppt

3. Potassium chromate test: OS +K2CrO4 = yellow ppt

Group II - Cu2+ (copper):OS + dil HCl + H2S = black ppt

1. Throw off extra sol, retain ppt,

and dissolve in a few drops ofconc HNO3 = bluish green sol,ppt dissolves; divide into twoparts1. Part 1 + excess NH4OH = blue

coloured sol2. Potassium ferrocyanide test:

Part 2 + acetic acid +

K4[Fe(CN)6] = reddish brown /chocolate coloured ppt (Note -this test is difficult to get)

Group III - Fe2+, Fe3+ (iron),Al3+ (aluminium):OS + solid NH4Cl + excess NH4OH

1. Fe2+ / Fe3+: Note - ferrous saltsare green in colour, ferric saltsare brown in colour.

8 K2HgI49 Original solution: Salt + acid + water

1. If ferrous salt has been given,convert to ferric: OS + concHNO3 + heat = brown ppt;then do reaction with groupreagent

2. Brown ppt + HCl; then divide

into two parts1. Potassium ferrocyanide

test: Part 1 + K4[Fe(CN)6] =blue ppt / colour

2. Potassium thiocyanatetest: Part 2 + KCNS = bloodred colour

2. Al3+: Gelatinous white ppt1. Blue lake test: Retain ppt + dil

HCl = clear sol

1. Sol + blue litmus andNH4OH (drop-by-drop) =blue colour layer ('lake')floats over colourless sol

Group IV - Co2+ (cobalt), Ni2+(nickel), Mn2+ (manganese), Zn2+(zinc): OS + solid NH4Cl + excessNH4OH + pass H2S gas

1. Co2+ / Ni2+: Black ppt; dissolveppt in aqua regia 10 andevaporate sol to dryness to getresidue

1. Co2+: Blue residue; turnspink / purple when dissolvedin water; divide into two parts

1. Part 1 + dil acetic acid +KNO2 + warm = yellow ppt

2. Part 2 + ether (1 mL) +solid NH4CNS 11 = bluecolour in ether

2. Ni2+: Yellow residue; turnsgreen when dissolved inwater; divide into two parts

10 Aqua regia: 3 parts conc HCl + 1 part

conc HNO311 Ammonium sulphocyanide


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1. DMG 12 test: Part 1 +excess NH4OH + DMG =bright red ppt

2. Part 2 + NaOH + brominewater + boil = black ppt

2. Mn2+: Buff / skin colour ppt;divide into two parts1. Part 1 + dil HCl + boil off H2S

+ NaOH = white ppt; whichturns black / brown on addingbromine water

2. Lead dioxide test: Part 2 +PbO2 + conc HNO3 + boil =after cooling; pink colouration

3. Zn2+: Greyish white ppt; divide

into two parts1. Part 1 + excess NaOH = white

ppt dissolves2. Potassium ferrocyanide test:

Part 2 + K4[Fe(CN)6] = white /bluish white ppt

Group V - Ba2+ (barium), Sr2+

(strontium), Ca2+ (calcium):

OS + (NH4)2CO3 + NH4Cl + NH4OH =white ppt; add dil acetic acid, divide solinto three parts and test for followingIN ORDER

1. Ba2+: Part 1 + excess K2CrO413

(aq) = yellow ppt

2. Sr2+: Part 2 + (NH4)2SO4 (aq) =white ppt

3. Ca2+: Part 3 + (NH4)2C2O414 (aq)+ NH4OH (only if nothing appearsat first) = white ppt

4. Flame test: Take salt and makea paste by mixing with conc HCl.Take paste on tip of glass rod /platinum wire, and put in Bunsenburner flame1. Ba2+: Green flame2. Sr2+: Crimson red flame3. Ca2+: Brick red flame

12 Dimethyl glyoxime reagent

13 Potassium chromate14 Ammonium oxalate

Group VI - Mg2+ (magnesium): Nogroup reagentOS + NH4Cl + excess NH4OH +ammonium phosphate = white ppt

Colour Inference

Blue Cupric salts

Green Hydrated nickelsalts

Rose red Cobalt salts, HgI2

Light green Ferrous salts

Yellow / brown Ferric salts

Green / blue Hydrated coppersalts

Deep blue Anhydrous cobaltsalts

Pale pink Manganese salts

Dark green / Chromic saltspurple

Miscellaneous Notes

With Br-, most labs only haveNH4+.

With Ca2+, most labs only haveCl-.

Easier way to do flame test: Usetest tube holder as tongs, and

pick up a sizeable chunk of saltwith it. Put one drop of conc HCl,and put in Bunsen burner flame.

Do flame test first; if you're luckyyou'll get your cation early. Moststudents spend up a lot of timedoing cation test.

chemistry salt analysis cheat sheets

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